Which energy type involves atomic nuclei and changes within the nucleus?

• A. Nuclear
• B. Electrical
• C. Chemical
• D. Thermal

Answer: (A)

Nuclear energy refers to energy stored in and released from atomic nuclei, through changes inside the nucleus such as fission or fusion. In fission, a heavy nucleus splits into smaller nuclei, releasing a large amount of energy; in fusion, light nuclei join to form heavier ones, also releasing energy. These processes involve the strong nuclear force and mass–energy conversion, which is why the energy comes from the nucleus itself. This distinguishes it from electrical energy, which comes from moving charges; chemical energy, which arises from bonds between atoms and electrons; and thermal energy, which relates to the random motion of particles and temperature.